SWO1 modulates cell wall integrity under salt stress by interacting with importin ɑ in Arabidopsis

Maintenance of cell wall integrity is of great importance not only for plant growth and development, but also for
the adaptation of plants to adverse environments. However, how the cell wall integrity is modulated under salt
stress is still poorly understood. Here, we report that a nuclear-localized Agenet domain-containing protein SWO1
(SWOLLEN 1) is required for the maintenance of cell wall integrity in Arabidopsis under salt stress. Mutation in
SWO1 gene results in swollen root tips, disordered root cell morphology, and root elongation inhibition under salt
stress. The swo1 mutant accumulates less cellulose and pectin but more lignin under high salinity. RNA-seq and
ChIP-seq assays reveal that SWO1 binds to the promoter of several cell wall-related genes and regulates their
expression under saline conditions. Further study indicates that SWO1 interacts with importin ɑ IMPA1 and IMPA2,
which are required for the import of nuclear-localized proteins. The impa1 impa2 double mutant also exhibits root
growth inhibition under salt stress and mutations of these two genes aggravate the salt-hypersensitive phenotype
of the swo1 mutant. Taken together, our data suggest that SWO1 functions together with importin ɑ to regulate
the expression of cell wall-related genes, which enables plants to maintain cell wall integrity under high salinity.